My first attempt will be with kites because they are less dangerous than hydrogen balloons and easy to build for cheap. The main question is "Can my kite lift my electronic device up ?" and it's not an easy one. The answer depends on many variables (wind speed, type of kite, ...) so I'm going to answer it empirically.
I've started by measuring the mass of a typical electronic device, that way I can use a load of the same mass for my first flights without the risk of breaking some expensive things.
Here's the results :
- Arduino uno : 21 g
- Raspberry Pi : 42 g
- AAA Battery : 24 g
I made a small bag for the load that I can fill with rice or sand. I've planned my first test for Tuesday with a 100 g load. The kite will be made of a single A4 paper sheet and a wooden skewer.